Apparatus for drying films



fm. 6, am. H HAMPEL 1,787,520

APPARATUS FOR DRYING FILMS Filed Aug. 8, 1928 4 Sheets-Sheet l Jan.. 6, QEB. H, HAMPEL 1,787,520

APPARATUS FOR DRYING FILMS Filed Aug. 8, 1928 45 Sheets-Sheet 2 W @www Jam., 6, HQBL H. HAMFEL APPARATUS FOR DRYING FILMS Filed Aug. 8, 1928 4 Sheets-Sheet L www m ww d ff www .wwwa n, .m m@

Jam. @9 WM., H. HAMPEL APPARATUS FOR DRYING FILMS Filed Aug. 8, 1928 l Sheets-Sham 4 Patented Jan. 6, 1931 UNITED STA-TES PATENT OFFICE APPARATUS FOB DRYING FILMS Application iled August 8, 1928, Serial o. 298,318, and in Germany July 2, 1926.

This invention relates to a machine intended for drying endless lms obtainedv from plastic materials which have to undergo considerable shrinkage in drying. It is especially lit for drying cellulosic films obtained from viscose, the shrinkage ofwhich can be from The novel drying apparatus hereinafter described is illustrated in the accompanying drawings. Y

The principle of the invention is illustrated in Figs. 1v and 2.

Fig. 1 shows a side elevation of the new drying device.

Fig. 2 is a view in front of theV first drying drum.

A further example of the invention is illustrated in Figs. 3 and 4.

Fig. 3 shows a transverse section.

Fig. 4 is a side-view.

. Another improved example of the invention is shown in Figs. 5 and 6.

Fig. 5 is a transverse section.

Fig. 6 is a side-view.

Fig. 7 shows a special form of the drying device in side-view.

The essential features of the novel device are iirst illustratedv in Figs. 1 and 2 of the accompanyingv drawings.

There are a series of tubular members 1, 2, 3 and4 the exterior cylindrical surfaces of which are polished smooth and which rest at both ends on pulleys 5, the latter preferably each being furnlshed with a flange 6.

35 As will be readily understood, each drying cylinder rests in all on four friction pulleys 5.

The latter are, for example, journaled in suitable bearings 7 and driven from both sides by means of bevel wheels 40 or friction gear,

v from a main shaft 41 actuated by a motor 42.

The film f passes in succession around the separate drums 1 to 4 the surface of which is brought to the temperature requisite for the drymg by means, for example of internally disposed ribbed tubes 8.

y when longitudinal shrinkage arises in order The important feature of the new device resides in none of the drying rolls being given a rigid drive. On the contrary, they all rest loosel'yaonly on the pulleys ,5 and roll, on the rotation of the latter, in the opposite sense thereto due to the friction between the engaging surfaces.

Theadvantage thus attained is that V`the shrinking film, after it has acquired a certain tension, holds back individual rolls so that they slip back somewhat on the running surfaces of thel pulleys 5 and consequently, rotate more slowly than the preceding rolls, precisely in the manner required by the contraction in length occurring during thedrying.

By the arrangement herein described is further attained that the friction acting lbetween the adjacent rolling surfaces decreases that the corresponding loose rolls may hold back in their movement.

1f considerable drying-shrinkage occurs between, for example, the rolls 2 and 4 then this tends to lift the roll 3 from its friction pulleys. The friction effecting the drive is thus destroyed or reduced, resulting in the particular roll becoming stationary or holding back.

This tendency resulting from lthe longitudinal contraction of the film is A'limited y the relation which exists between the breaking-strength or extensibility of the travelling film and the weight of the drying rolls. The said weight may be regulated within Wide limits however, so that it is possible in a very simple manner to adapt exactly the tension, at which the shrinkage should occur, to the particular material.

The herein described device offers moreover, a further advantage.

The longitudinal shrinkage of the travelling film is already taken into account in a manner completely satisfactory in itself in that all the surfaces coming in contact therewith are moved non-positively byrolling on rigidly driven pulleys. Beyond this 1t is possible to follow the film-shrinkage also by alteration of the velocity imparted .to the pulleys 5` or the degree within which the shrinkage is to be 'elded to may thus be precisely adjusted or each roll during operation.

Finally, it may be observed that the present drying device is of'particularly simple construction by reason of the exclusive use of simple exteriorly polished tubes which rest on tlm belt pulle s 5 commercially available and byreason o the possibility of effecting the internal heating of the rolls, without a stuiiing box by means of rigidly mounted heating tubes.

The above explanations have up to the present /only related to the longitudinal shrinkage occurring on drying. At the same e time however, the transverse shrinkage must also be considered. This must be yielded to in an appropriate'manner by allowing the width of the film to decrease perfectly uniformly and without tearing.

Per se it is again known to conduct endlessv formations such as paper and woven webs, with opposite sides alternately bearing, over drying rolls arranged in one or two rows and disposed as closely as possible together in order the better to utilize the surface. Although any formation which traverses such drying apparatus will suffer a certain shrinkage on the removal of the water, this is however, not very large and it is scarcely necessary in the paper and textile industry, therefore, to take it into special consideration. It is usually possible to allow the paper and woven webs in question to bear on the same drying surface until completely dried without tearing or other damage being caused by the transverse shrinkage.

The conditions are, however, quite different in the case of the drying of strongly shrinking films, particularly viscose films.

In this instance the entire transverse shrinkage cannot be equalized at once. If a moist film of moderately considerable width were ke t stretched, until the water has been fully tak bearing on rylng surfaces, then it would tear during orafter the drying due to the excessive stresses resulting.

For this reason, such ilmsare turned, in the manner of the paper-industry, from roll to roll so that the stress caused on the receding drying surface may be e ualize in small amounts intermittently, eac time between two rolls, in vaccordance with the progressive drying.

It has been found in connection with the device illustrated on Fig. 7 that it is preferable to select the diameters of the successive drying rolls in such a manner that they increase inthe direction of progression of the en u by side bands or by its tight v and at the commencement of the dryin experiences a comparatively large shrin age. It is therefore advanta eous to turn it, at the start, as often as possi le from roll to roll, that is to make it run over rolls with the smallest possible diameter. As the removal of the water proceeds the strength-properties of the film improve and the diameter of the Adrying rolls may accordingly increase, particularly also as the extent of the shrinkage falls olf materially.

The distance between successive drying rolls is thus dependent upon the extent of the shrinkage. With the roll diameter increasing in the direction of progression of the drying approximately the amount of shrinkage is equalized everywhere. The individual rolls may therefore all be at the same relative distance from one another, this being made as small as possible, on account of the'space requirements.

The drying device operatin in accordance with the Figures 1 and 2 of le accompan ing drawings allows without dilficulty of t e use of drying cylinders with different diameters. Rolls of quite different circumference may be mounted upon the various sets of friction pulleys 5. If the linear velocity of the latter is kept the same the individual drying rolls will have the same circumferential velocity in spite of the different diameters. On the otherhand, the use of the friction pulleys 5 also presents the possibility of adapting the speed of transport of the travelling film to the adually arisin longitudinal contraction decreasing t e diameter the speedof revolyiltion remaining the same, or by decreasing the revolutions, the diameter remainin the same, the decrease in each instance being in the direction of progression of the drying.

The principle, described and justified in the above, of the novel device for drying badly-shrinking films, particularly for d ing viscose films, may be applied technical y in the most varied ways. The accompanying drawings merely give a few examples thereof. v

The sim lest case has been shown in Fi 1 and 2 a ready described. There the fi llo travels over a row of horizontally disposed Y This row of rolls may naturally also be arranged vertically in the manner of a calender.

A further example is illustrated in Figs.

3 and 4 of the accompanying drawings.

This concerns an upper row of rolls 9, 10 and 11 which are given on positive drive and a lower row of rolls 12, 13 and 14 which rest on the friction pulleys 15 and are caused to rotate, on rotation of the latter, by rolling thereon. The supply of heat is eected in the case of the upper rolls by, for example, the usual internal heating and in the case of the lower rolls by means, for example, of

the internal tubes 16 with radiator fins rection andtheir number is thus reduced to one half. Thepulleys are driven as before by motor 42, bevel gears 4() and shaft 41 or in any other suitable manner.

If it is desired to bring the upper and lower rows of rolls very close together and, nevertheless to drive all the rolls by friction pulleys, then the arrangement shown in Figs. 5 and 6 is preferably employed.

The upper rolls 17 rest on the end friction pulleys 18 and are somewhat longer than the lower drying cylinders. The shafts 20 on each of which two of the pulleys 18 are secured, penetrate the lower drying cylinders 19. The latter consist of simple tubular members and are somewhat shorter than the upper rolls 17. They are driven by the pulleys 21 which are mounted two on each of the shafts 22. The heating is effected by the internal radiator tubes 23. The pulleys 18 and 21 are furnished with flanges which prevent lateral displacement of the rolls. rThe shafts 20 and 22 are driven by shaft 41 and bevel gears 40 from a motor 42 as before, or in any other manner.

Precisely as in the textile industry, the web of material is treated in a cylinder drying machine, the film f bears with opposite sides alternately around the separate rolls of the two superimposed rows.

Finally in Fig. 7 of the accompanying drawings a further example of the above descri-bed drying device, with rolls having different diameters is illustrated. It is constructed in the same mannerv as the device shown in Figs. 5 and 6 and actuated by motor 42, through shaft 41 and bevel gears 40 as before, or in any other suitable manner.

rlhe rolls 24 of the upper row have increasing diameter, as have the rolls 25 of the lower row, in the direction of progression of the drying. The upper rolls rest on the pulleys 26 and the lower rolls on the pulleys 27. Exactly as in Fig. 6 the rolls 24 are longer than th rolls 25 to make room at both ends for the friction pulleys 26 the shafts 28 of which pass through the lower cylinders 25. The heat is supplied through the radiator tubes 29. The moist film f is introduced into the drying apparatus over the roll 30 and is Wound in a dry condition at the end of said.

apparatus on the collecting roll 31.

The number of separate rolls requisite for any of the drying devices illustrated in the accompanying drawings depends upon the length of (web travelling through per unit of time and upon the desired drying period. It is in any case preferable to use a large number of rolls of small diameter than rolls of larger diameter.

I claim:

1. A device for the continuous drying of films, particularly viscose films, including short flanged pulleys, a row of rolls over which the lm is adapted to be driven frictionally and exclusively, resting at their ends on said pulleys, means for rotating said pulleys and consequently also said rolls indirectly and in opposite direction, said rolls increasing in diameter progressively in the direction of drying.

2. A`device for the continuous drying of films, particularly vicose films, including short flanged pulleys, a row of rolls over which the lm is adapted to be driven frictionally and exclusively, resting at their ends on said pulleys, means for rotating said pulleys and consequently also said rolls indirectly and in opposite direction, said rolls increasing in diameter progressivelyin the direction of drying, and accordingly being rotated at effective rotational speeds decreasing in the direction of progression of the drying.

3. A device for continuous drying of films, comprising an upper and a lower row of hollow rolls adapted to carry the films, a series of pairs of flanged upper pulleys mounted on individual vshafts positively driven in one direction, a series of pairs of flanged lower pulleys similarly mounted'and positively driven in opposite direction to t said upper pulleys, said upper and lower rows of rolls contacting with the surfaces of the corresponding pulleys and between the flanges thereof, a heating element within each of said rolls, the shafts of said upper pulleys extending through the respective rolls of the lower row, and said lower rolls having substantially the same length as the space between a pair of said upper pulleys.

4.- A. device for continuous drying of films, comprising an upper and a lower row of hollow rolls adapted to carry the films, a series of pairs of flanged upper pulleys mounted on individual shafts positively driven in one direction, a series of pairs of flanged lower pulleys similarly mounted and positively driven in opposite direction to said upper pulleys, said u per and ylower rows of rolls contacting with the surfaces of the correspondinging pulleys and between the flanges thereof, a heating element within each of said rolls, the shafts of said upper pulleys extending through the respective rolls of the lower row, and said lower rolls having substantially the same length as the space between a pair of said upper 1pulleys, the diameter of each succeeding rol greater than the diameter of its predecessor 1n the respective rows.

In testimony whereof I ax my si DR. HEINRICH H ature. PEL.

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